(Combined Sources) Slow down when you drive into Greenfield. The Department of Public Works is replacing 30 MPH signs with 25 MPH signs at entryways to the city. Back in May, the Greenfield City Council voted to replace the signs and also proposed lowering the speed limit on many side streets. The entryways where the limit has been lowered includes the Mohawk Trail, Bernardston Road, Leyden Road, the French King Highway and Deerfield Street.